Stable dishwashing compositions containing sodium dichloroisocyanurate dihydrate

ABSTRACT

A dishwashing composition having high stability against loss of available chlorine is formulated to contain 0.5 to 10 percent by weight of sodium dichloroisocyanurate dihydrate, 5 to 65 percent of an alkali metal silicate, 20 to 60 percent of a compound having water softening and detergent building properties, usually sodium tripolyphosphate, 0.5 to 10 percent of a low-foaming chlorine-compatible nonionic surface active agent, and 0 to 50 percent of filler, usually sodium carbonate.

United States Patent [191 Corliss STABLE DISHWASI-IING COMPOSITIONS CONTAINING SODIUM DICHLOROISOCYANURATE DII'IYDRATE Related US. Application Data Continuation-in-part of Ser. No. 309,277, Nov. 24, 1972, abandoned.

Inventor:

U.S. Cl 252/99, 252/95, 252/187 C Int. Cl Clld 7/56 Field of Search 252/99, 95, 187 C References Cited UNITED STATES PATENTS 12/1970 Kitchen et a1. 252/99 June 11, 1974 3,575,865 4/1971 Burke et al. 252/99 Primary Examiner-Mayer Weinblatt [57] ABSTRACT A dishwashing composition having high stability against loss of available chlorine is formulated to contain 0.5 to 10 percent by weight of sodium dichloroisocyanurate dihydrate, 5 to 65 percent of an alkali metal silicate, 20 to 60 percent of a compound having water softening and detergent building properties, usually sodium tripolyphosphate, 0.5 to 10 percent of a low-foaming chlorine-compatible nonionic surface active agent, and 0 to 50 percent of filler, usually sodium carbonate.

5 Claims, No Drawings STABLE DISHWASHING COMPOSITIONS CONTAINING SODIUM DICHLOROISOCYANURATE DIHYDRATE CROSS-REFERENCE TO RELATED APPLICATIONS This is a continuation-in-part of Ser. No. 309,277, filed Nov. 24, 1972, now abandoned.

This invention relates to detergent compositions use ful as cleaners and, more specifically, to those compositions containing sodium dichloroisocyanurate dihydrate which are useful in household automatic dishwashing machines.

In the formulation of household automatic dishwashing compositions, the usual practice is to incorporate chlorinating agents, such as chlorinated isocyanurates, alkaline silicates, known detergent builders such as sodium tripolyphosphate, low-foaming chlorinecompatible nonionic surfactants, and, optionally, fillers such as sodium carbonate.

A serious problem with these compositions is their rather poor stability as manifested by loss of available chlorine during storage. A number of solutions to this problem have been put forward, as for example US. Pat. No. 3,390,092 to Keast et al. wherein the chlorine stability of automatic dishwashing fonnulations was enhanced by incorporation of a white paraffin oil.

But despite these marked advances, chlorine losses in automatic dishwashing compositions have not been reduced to the desired minimum. As a consequence, considerable effort is being expended in an effort to develop even more stable formulations.

It has now been found that dishwashing compositions having improved stability against loss of available chlorine contain by weight the following essential ingredients:

1. Sodium dichloroisocyanurate dihydrate. From about 0.5 to about 10 percent, preferably about 1 to about 5 percent.

2. An alkali metal silicate having a M to SiO weight ratio of about 1:3.3 to 1:1, M being either sodium or potassium. From about to about 65 percent, preferably about 20 to about 65 percent.

3. A compound having water-softening and detergent building properties, preferably a polyphosphate having an R 0 to P 0 mol ratio of 1:1 to 2:1, R being either sodium or potassium. From about 20 to about 60 percent, preferably about 30 to about 50 percent.

4. A low-foaming nonionic surface active agent compatible with chlorinated isocyanurates. From about 0.5 to about percent, preferably about 1 to about 5 percent.

5. Filler, usually sodium carbonate or sodium sulfate, or mixtures of these; essentially the balance of the compositions, usually from about 0 to about 50 percent.

Since the presence of moisture tends to accelerate loss of available chlorine in automatic dishwashing compositions containing chlorinated isocyanurate, it is indeed surprising that higher stability against chlorine loss is realized by replacing sodium dichloroisocyanurate with the dihydrate form which contains about 14 percent water. As yet no explanation is known which would account for such enhanced stability.

Sodium dichloroisocyanurate dihydrate is a known chemical entity which is documented extensively in the 2 patent literature. Its description and preparation is disclosed in US. Pat. No. 3,035,056.

In the present formulations the sodium dichloroisocyanurate dihydrate component: provides available chlorine which aids in the cleaning action and acts as an excellent destainer and germicide. The particle size of the sodium dichloroisocyanurate dihydrate has not been found critical; in general, any granular product can be used with good effect.

The nonionic surfactant components result in a preparation high in food soil defoaming power, i.e., a preparation which has little or no tendency to foam by itself or in the presence of a foam-producing food soil. The nonionic surfactant employed must have a combination of three properties: (1) it must be a low-foaming material; (2) it must be capable of defoaming food soils such as milk; and (3) it must be compatible with chlorinated isocyanurates, that is, it must not decompose these chlorinated compounds markedly in the formulation.

Nonionic surfactants which meet these requirements include the lower alkyl ethers of polyoxyethylated octylphenols such as those sold under the Triton CF trade name, for example Triton CF-54l which is the butyl ether of polyoxyethylated octylphenol; an alkylether of polyoxyethylated alkanol such as Triton DF12"; polyoxyalkylene glycols having a plurality of alternating hydrophobic and hydrophilic polyoxyalkylene chains, the hydrophilic chains consisting of linked oxyethylene radicals and the hydrophobic chains consisting of linked oxypropylene radicals, said product having three hydrophobic chains linked by two hydrophilic chains, the central hydrophobic chain constituting 3O to 34 percent by weight of the product, the terminal hydrophobic chains together constituting 31 to 39 percent by weight of the product, the linking hydrophilic chains together constituting 31 to 35 percent by weight of the product, the intrinsic viscosity of the product being from about 0.06 to 0.09 and the molecular weight of the product being from about 3,000 to 5,000, all as described in US. Pat. No. 3,048,548; the alkyl polyoxyalkylene ether alcohols based on straight chain -biodegradable hydrophobic segments, for example Tretolite H-0307-S"; and the water soluble benzyl ether of octylphenol condensed with ethylene oxide. Other nonionic surfactants are suitable for use in the herein dishwashing preparations and it is not intended to exclude any surfactant possessing the above properties.

The builder component functions as a water softener and a detergent builder. Polyphosphates of commerce, having an Na O or K 0 to P 0 mol ratio of about 1:1 to 2:1 can be used. Typical polyphosphates of this kind are the preferred sodium tripolyphosphate, sodium hexametaphosphate and sodium pyrophosphate as well as the corresponding potassium polyphosphates. The particle size of the polyphosphate is not considered critical and any finely divided commercially available product can be employed. Non-phosphate builders and water softeners are suitable also such as for instances nitrilotriacetic acid (NTA); Polycarboxlic acids formed from the polymerization of polycarboxylic monomers and described in US. Pat. No. 3,308,067 and related polyelectrolytes.

In the present formulation the alkali metal silicate acts as a detergent builder and enhances the cleaning action. The silicate also acts as a corrosion inhibitor for metal parts of the dishwashing machine.

7 Typical alkali metal silicates which can be used in the formulation are those having an M to SiO ratio of about 1:33 to 1:1 and containing about 0 to about percent of water. These include sodium metasilicate anhydrous and sodium metasilicate S-hydrate, GD Silicate also called disilicate, which is a product having an Na O to Si0 ratio of 1:2 and typically available in the form containing bound water in the amount of 18.5 percent, and G Silicate, which has an Na O to SiO ratio of 123.22 and a typical water content of about 19 percent.

While the above constitutes the essential ingredients of the composition it is to be understood that additional ingredients such as fillers, e.g., sodium chloride, sodium sulfate, etc., coloring agents and perfumes may also be added without departing from the basic formulation. All components are by weight based on the composition.

While the above ingredients may be mixed in any desired order, best results are obtained when the nonionic surfactant is added to the alkali metal silicate and the alkali metal carbonate (if used) with good mixing. This is also desirable because the nonionic surfactant is a liquid and is readily absorbed by the particulate alkali metal silicate and alkali metal carbonate. In preparing the formulation, the alkali metal silicate and alkali metal carbonate are mixed with the nonionic surfactant followed by the addition of sodium tripolyphosphate and sodium dichloroisocyanurate dihydrate. Each of these ingredients is added with vigorous mixing so that the particulate formulation is substantially homogeneous with a minimum of segregation of any given ingredients. Normally it is advisable to use ingredients having approximately the same particle size in order to prevent segregation on storage.

The following examples are given to illustrate the present invention and are not deemed to be limiting thereof. All components are given in terms of percentage by weight and add up to 100 percent.

EXAMPLE 1 Formulation Component 1 11 111 Available chlorine as chlorinated isocyanurate 1 1.5 1.5 1.5 Sodium tripolyphosphate 30.0 30.0 30.0 Nonionic surfactant (Plurafac RA 43) 3.5 3.5 5.0

Sodium carbonate 0.0 25.0 15.0 Sodium merasilicate S-hydrate Balance 0.0 0.0 Sodium metasilicate anhydrous 0.0 Balance 0.0 Sodium disilicate (18.5% water) 0.0 0.0 Balance A condensation product of an aliphatic, straight chain primary alcohol with ethylene oxide sold by the BASF-Wyandotre Co.

Available chlorine analyses before and after the storage period gave the following results.

TABLE 1 Available Chlorine As the results of Table I show, incorporation of sodium dichloroisocyanurate dihydrate (NaDCC-211 0), instead of anhydrous sodium dichloroisocyanurate (NaDCC) or potassium dichloroisocyanurate (KDCC), in household automatic dishwashing detergents gives markedly improved storage stability.

What is claimed is;

l. A dishwashing detergent composition having good stability against loss of available chlorine and consisting essentially of on a percent weight basis:

1. sodium dichloroisocyanurate dihydrate; from about 0.5 to about 10 percent;

2. an alkali metal silicate having 21 M 0 to SiO mol ratio of 1:3.3 to 1:1, M being either sodium or potassium; from about 5 to about 65 percent;

3. detergent builder and water softener from about 20 to about 60 percent;

4. a low-foaming nonionic surface active agent compatible with chlorinated isocyanurates; from about 0.5 to about 10 percent; and

5. a filler; from about 0 to about 50 percent.

2. The composition of claim 1 in which the alkali metal silicate is sodium disilicate.

3. The composition according to claim 1 wherein (3) is a polyphosphate having an R 0 to P 0 mol ratio of 1:1 to 2:1, R being either sodium or potassium.

4. The composition according to claim 3 wherein (3) is sodium tripolyphosphate.

5. The composition according to claim 1 wherein (5) is selected from the class consisting of sodium carbonate and sodium sulfate or mixtures thereof. 

2. The composition of claim 1 in which the alkali metal silicate is sodium disilicate.
 2. an alkali metal silicate having a M2O to SiO2 mol ratio of 1: 3.3 to 1:1, M being either sodium or potassium; from about 5 to about 65 percent;
 3. The composition according to claim 1 wherein (3) is a polyphosphate having an R2O to P2O5 mol ratio of 1:1 to 2:1, R being either sodium or potassium.
 3. detergent builder and water softener from about 20 to about 60 percent;
 4. a low-foaming nonionic surface active agent compatible with chlorinated isocyanurates; from about 0.5 to about 10 percent; and
 4. The composition according to claim 3 wherein (3) is sodium tripolyphosphate.
 5. The composition according to claim 1 wherein (5) is selected from the class consisting of sodium carbonate and sodium sulfate or mixtures thereof.
 5. a filler; from about 0 to about 50 percent. 